Standard Sport understands a move worth over £50m was agreed as far back as October as Blues continue to revamp their squad under the Todd Boehly-Clearlake Capital ownership.
Despite on-field struggles this season, the American owners are committed to investing in Graham Potter’s squad as they attempt to challenge for top honours once more.
Joao Felix, albeit initially on a short-term loan, Benoit Badiashile and Mykhaylo Mudryk have already arrived this month to take Chelsea’s spending to over £400m in under a year.
Nkunku moved to Germany from Paris Saint-Germain in 2019 and has since emerged as one of Europe’s leading attackers.
The west London giants were eager to steal a march on rivals for Nkuku’s signature, and duly moved quickly outside of the transfer window by agreeing to pay more than his £53m release clause, which actives this summer, to ensure they won the race.
The France international has won a raft of individual awards since moving to the Bundesliga after scoring 64 goals while laying on a further 51 assists in 159 appearances.
Speaking to BILD, Eberl said: “The signs are very, very clear that he’s moving to Chelsea.”